PL179604B1 - Method od and system sampling and determining presence of impurities in recycled plastic materials - Google Patents

Abstract

1. METHOD OF SAMPLING AND DETERMINING THE PRESENCE OF POLLUTANTS IN PLASTIC MATERIALS FROM RECYCLED PROCESSING AND SENT FOR THE PRODUCTION OF NEW CONTAINERS, CHARACTERIZED IN THAT THE INPUT IS SUPPLIED IN USED FORM CONTAINERS, THEN BREAK EACH CONTAINER 1 USING THE INCREASE THE TEMPERATURE RESULTING FROM THE BREAKING OF CONTAINERS, EVAPORATED POLLUTANTS EMITTED IN THE FORM OF VOLATILE SUBSTANCES ARE IMMEDIATELY COLLECTED AND TESTED FOR THE PRESENCE OR ABSENCE OF CONTAINERS IN THESE MATERIALS 11. SYSTEM FOR SAMPLING AND DETERMINING OBE VOLUME OF POLLUTANTS IN PLASTICS MATERIALS FROM PROCESSING SECONDARY MOVEMENT ALONG THE CONVEYOR, OBTAINED FROM USED CONTAINERS, AND SORTING THIS MATERIAL FOR SECONDARY PROCESSING FOR THE PRODUCTION OF NEW CONTAINERS, CHARACTERIZED IN THAT IT HAS A CONVEYOR (198) ON WHICH THE INDUCT FROM USED CONTAINERS (C) IS LOCATED, PI FIRST CONTROL STATION ( 200) TESTING USED CONTAINERS (C) FOR VOLATILE CONTAMINANTS, AFTER THE CONTROL STATION (200) THERE IS THE FIRST TEAM FOR 1 SEPARATING AND REMOVING CONTAMINATED CONTAINERS FROM THE CONVEYOR (198), AFTER WHICH THE SHREDDER IS LOCATED ( 202) EVERY REMAINING CONTAINER , SECOND CONTROL STATION (204) FOR VOLATILE SUBSTANCES, FOLLOWING THERE IS A SECOND TEAM FOR SEPARATING AND REMOVING PIECES OF MATERIAL CONTAINING CONTAMINANTS FROM THE CONVEYOR, A TEAM (206) FOR WASHING THE LEFT MATERIAL PIECES RIDING ON A CONVEYOR IN HOT LIQUID, THERE IS A THIRD STATION CONTROL (208) OF VOLATILE CONTAMINANTS FROM THE PIECES THAT HAVE BEEN WASHED AND FINALLY A THIRD TEAM FOR SEPARATING THE PIECES CONTAINING THE CONTAMINANTS FROM THE PIECES THAT ARE NOT CONTAINING THE CONTAMINANTS. FIG. 2 ( 1 2 ) 179604 PL PL PL PL PL

Description

The present invention relates to a method and system for selecting samples and determining the presence of contaminants in recycled plastic materials.

The present application is in part a continuation of US Pat. No. 5,352,611. In particular, the present invention relates to a method and a control system for sampling and determining the presence of certain substances, such as contaminant residues in the materials of plastic containers that come from collections. secondary materials such as polyethylene terephthalate (PET) beverage bottles or plastic food containers. More specifically, the present invention relates to an improved sampling and analyzing system and a method for determining the presence of contaminants in recycled plastic materials, such as e.g. beverage bottles, as the material quickly moves along the conveyor through a series of test stands. in the material washing and sorting system.

In many technical fields, including the beverage industry, products are packaged in containers which are returned, washed and refilled after use. Typically, refillable containers such as beverage bottles are made of glass that can be easily cleaned. These containers are washed and then tested for the presence of foreign matter.

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Glass containers have the disadvantage of being fragile and being relatively heavy at larger volumes. Accordingly, it is highly desirable to use plastic containers that are less fragile and lighter than glass containers of the same capacity. However, plastic materials can absorb numerous components which can then be absorbed into the stored product, affecting the quality of the product in the container. Examples of such ingredients include, but are not limited to, ammonia, organic nitrogen components, hydrocarbons including gasoline, and various cleaning fluids including soaps and detergents.

However, if these plastic containers, or the materials from which each container is made, can be reliably inspected with high sensitivity for contamination, contaminated plastic bottles or materials may be separated from uncontaminated containers or materials, and then good containers or materials are allocated for further use.

The above-mentioned US Patent No. 5,352,611 describes inspection methods for determining the presence of contaminants in the plastic beverage containers used, or a particulate or flaked plastic material from which the containers are made.

The present invention aims to improve the solutions described in the earlier patent specification No. 5352611 relating to the re-use of plastic materials from which used plastic beverage containers are made.

In order to allow used plastic materials, such as PET beverage bottles, for the production of new bottles, it is necessary to state that the secondary material does not contain any of the potentially harmful components of the types described above.

Although various steps are taken to remove undesirable plastic contaminants in the incoming stream of beverage bottles, the bottles are then broken up and the particulate plastic material is completely washed so as to remove potentially harmful contaminants from the fragmented or cut plastic material. flaps of material, there is a need for improved control of secondary plastic materials. In particular, it would be beneficial to have real-time chemical monitoring of secondary plastic materials, such as bottles or their sheets, at any stage of the process, in particular at any stage of pretreatment including sorting, cleaning, washing, cutting, pelletizing and pre-forming and / or making bottles to ensure that heavily contaminated material is removed from the secondary material.

Accordingly, the main object of the present invention is to provide a method and system for detecting the presence or absence of specific substances, such as impurities containing, for example, but not limited to, ammonia, organic nitrogen components and hydrocarbons, in plastic materials.

Another object of the present invention is to provide a method and system for detecting specific contaminants in articles made of plastic materials, or in comminuted, pelleted or cut plastic material as the articles or materials pass along the conveyor.

Another object of the present invention is to provide a system and method for sampling and analyzing residues in materials as they pass along a conveyor.

Another object of the present invention is to provide a system and method for sampling and analyzing residues in materials moving along a conveyor without contacting the test materials with any of the analyzing and testing mechanisms.

Yet another object of the present invention is to provide a method for inspecting used plastic beverage containers for contamination, shredding the containers into their components, and washing these components in a continuous, linear process.

The method of sampling and determining the presence of contaminants in plastic materials from secondary processing and sent to pro

179 604 production of new containers, according to the invention, is characterized by the fact that the charge is supplied in the form of used containers, then each container is broken and taking advantage of the temperature increase resulting from breaking the containers, the evaporated possible pollutants emitted in the form of volatile substances are immediately collected and tested for the presence of or the absence of impurities in these materials.

The shredded plastic material breaks into strips.

The shredded material breaks, forming sheets of plastic material.

During testing, fluid is directed onto pieces of material, then at least some of the volatile substances emitted from the pieces of material are moved to positions remote from the materials to form a test cloud in an area remote from these materials, and some volatile substances are sampled by suction and analyzed. the collected sample, determining the presence or absence of contaminants in the materials.

Before testing the fragmented material, pieces of plastic material are additionally washed in a heated liquid, removing some of the impurities they contain, and the temperature of the washed material is kept below 343.3 ° C, at which there is no emission of vapors from the plastic materials themselves, PET .

In another variant, the method of sampling and determining the presence of contaminants in plastic materials from recycling and directed to the production of new containers, according to the invention, is characterized in that a batch of materials from which the used containers were produced is provided, the batch of materials is washed. in a hot liquid, after which some of the impurities contained therein are removed, the temperature of the washed material is kept below 343.3 ° C, volatile impurities are tested to determine the presence or absence of impurities in the PET materials.

During testing, the fluid is directed to pieces of material, moving at least some of the volatile substances contained in them to positions distant from the materials to form a test cloud, then a sample of some of the volatile substances is taken by aspirating a test cloud and analyzed for the presence or absence of contaminants in the materials.

In a further embodiment, the method of sampling and determining the presence of contaminants in the plastic materials traveling along the conveyor from used containers, and sorting this material for recycling for the production of new containers, is characterized in that a batch of used containers is provided to the conveyor , each used container is tested for the volatile contaminants it contains, the contaminated containers are separated and removed from the conveyor, each remaining container is broken and, using the temperature increase occurring when the containers are broken, the pollutants evaporated at this higher temperature and emitted from them are collected volatile substances, they are tested to determine the presence or absence of impurities in the materials, pieces of material containing impurities are separated and removed from the conveyor, pieces of material remaining on the conveyor in hot liquid are washed, the flight is tested debris from pieces that have been washed and separates the debris-containing pieces from the non-impurities.

During each test, the fluid is directed to the container or pieces of materials, moving at least some of the volatile substances contained in them to positions distant from the materials to form a test cloud, samples of the displaced volatile substances are taken by sucking the test cloud and the collected sample is analyzed. Additionally, the temperature of the washed material is kept below 343.3 ° C.

A system for sampling and determining the presence of contaminants in recycled plastic materials moving along a conveyor, obtained from used containers, and sorting this material for recycling for the production of new containers, according to the invention, is characterized in that it has a conveyor, where the batch of used containers is located, the first test station to test the used containers for volatile contaminants, after the test station there is the first unit for separating and removing the contaminated containers from the

179 604 of the carrier, followed by the shredder of each remaining container, the second control station for volatile substances, then there is a second unit for separating and removing pieces of material containing contaminants from the conveyor, a unit for washing pieces of material remaining on the conveyor in hot liquid, further there is a third volatile pollutant test station from the pieces that have been washed, and finally a third unit for separating the pieces containing impurities from the non-impurities.

Each test station includes an assembly for directing the fluid onto a container or pieces of materials, an assembly for collecting a sample of the resulting volatile substances, a suction assembly for collecting samples from a cloud in an area remote from the conveyed materials, and a assembly for analyzing the collected sample.

The system further comprises an assembly for keeping the temperature of the washed material located adjacent to the dishwasher below 343.3 ° C.

The applicability of the present invention will become apparent from the detailed description which follows. Of course, the following description and specific examples, while pointing to the preferred embodiments, are illustrative only, and various changes and modifications are possible without departing from the scope of the invention, and will become apparent to those skilled in the art from the detailed description.

The subject matter of the invention is shown in the embodiment in the drawing, in which Fig. 1 is a block diagram of the invention described in the prior art, illustrating a plurality of containers moving in series along the conveyor system through the inspection station, reject mechanism and washing station, Fig. 2 is a block diagram of the system and a method of inspecting, comminuting, washing and sorting secondary plastic materials in accordance with the present invention.

Figure 1 shows the conveyor 10 moving in the direction of arrow A, having a plurality of uncapped, unsealed, spaced apart containers C (e.g., plastic beverage bottles of approximately 1.5 liters) arranged thereon such that they slide in and out. through the inspection station 12, and the reject mechanism 28 and conveyor 32 to the washer system. For greater throughput, the containers C may be touching instead of being spaced apart. The contents of the containers C will normally consist of air, volatile substances of the residual contaminants, if any, and volatile substances of any products, such as beverages previously contained in these containers. The air injector 14, which is a source of compressed air, is provided with a nozzle 16 spaced apart but in alignment with the container C in the inspection station 12. That is, the nozzle 16 is located outside the containers and is not in contact with them. A nozzle 16 directs compressed air into the containers C to move at least a portion of the container contents, thereby emitting a test cloud 18 to an area outside the container under test.

_{Alternatively, a CO 2} gas cloud may be used as the injected fluid in place of the compressed air. Also, both the compressed air and the CO ₂ gas cloud can be heated to increase the volatility of the test components.

The volume of air injected through the nozzle 16 into the container C is generally in the order of 10 cm ³ to 50 cm ³ for a bottle speed of about 200 to 1000 bottles per minute. A speed of 400 to 600 bottles per minute is possible and is in line with current beverage filling speeds. The desired test speed may vary depending on the bottles tested and filled. Of course, the bottles can remain stationary or they can move at a speed of less than 200 bottles per minute and the system will continue to run. Only about 10 cm ^{3 of the} contents of the container should be moved to the areas outside the bottle to form a test cloud 18.

Also, a vacuum sampling device 22 is provided, which may include a vacuum pump or the like connected to a sampling tube or conduit 20. The tube is mounted nearby and advantageously downstream (e.g., about 1 / 6.3 cm).

179 604 from the air injector 14 so that it remains in contact with the test cloud 18 adjacent to the opening in the upper part of the containers C.

Neither the nozzle 16 nor the tube 20 is in contact with the containers C at the inspection station 12, rather, they are positioned at some distance from the outside of the containers near their inlets. This has the advantage that no physical connection to the containers C is required, nor is any insertion of the samplers into the containers, which would obstruct rapid movement along the conveyor 10 and thus slow down the sampling rate. High sampling rates of about 200 to about 1000 bottles per minute are achievable with the apparatus and method of the present invention. The conveyor 10 is preferably continuously driven to achieve these speeds without stopping or slowing down the bottles at the inspection station.

A bypass path 24 is provided in conjunction with a vacuum sampling device 22 such that a predetermined portion (of preferably about 90%) of the sample from cloud 18 entering tube 20 can be drained through the bypass path 24. The remainder of the sample passes to a residue analyzer 26 which is determines whether any undesirable substances are present, after which it is removed. One purpose of diverting a large portion of the sample from cloud 18 is to reduce the size of the sample passing from the vacuum sampler to the debris analyzer 26 for faster analysis speed. This is done to supply processable sample levels to the debris analyzer 26. Another purpose of diverting a portion of the sample is to allow the vacuum sampler 22 to remove substantially all of the sample cloud 18 from the test bench area and remove the excess through the bypass path 24. In a preferred embodiment the portion is the excess sample traversing the bypass path 24 is returned to the air injector 14 for introduction through the nozzle 16 into subsequent containers moving along the conveyor 10. However, it is also possible to provide an outlet for the bypass path 24 to the atmosphere.

It should be clear that sample cloud 18 can be analyzed on-site without transporting it to a remote scrap analyzer 26. It can also be transported to the analyzer by blowing rather than suction.

A microprocessor controller 34 is provided to control the operation of the air injector 14, the vacuum sampler 22, the debris analyzer 26, the rejection mechanism 28, and an optional fan 15. The bin detector 17, including the radiation source and the photo detector together, is located on the side opposite the reflector (not shown) across the conveyor 10. The detector 17 informs the controller that the container is moving to the inspection station and briefly interrupts the radiation beam reflected to the photo detector. An optional fan 15 is provided to create a blast of air towards the test cloud 18 and preferably towards the movement of the containers C to assist in the removal of the test cloud 18 from the vicinity of the test station 12 after the sampling for each of the subsequent containers C. This clears the air. in the area of the test station so that no residues of the present test cloud 18 will be allowed to contaminate the area of the test station when another container C is in that station and is sampled. Hence, mixing of samples of adjacent containers is excluded. The cycle of fan 15 is controlled by a microprocessor 34 as schematically shown in Fig. 1. Preferably, fan 15 is run continuously for as long as the rest of the system is operating.

The rejection mechanism 28 receives a rejection signal from the microprocessor 34 when the scrap analyzer 26 determines that a given container C is contaminated with residues of various unfavorable types. The rejection mechanism 28 diverts the contaminated discarded bottles to the conveyor 30 and allows clean, acceptable bottles to pass into the dishwasher (not shown) on the conveyor 32.

An alternative option is to place the bottle inspection station on the exit side of the bottle washer in the direction of travel of the conveyor, or to place an additional inspection station, sampling and analysis system, downstream of the dishwasher. In fact

179 604 it may be advantageous to locate the inspection station and system downstream of the dishwasher to inspect bottles due to the presence of some contaminants. For example, if the contaminant is a hydrocarbon such as oil which is insoluble in water, it is easier to detect the remaining hydrocarbons after washing the bottles first. This is because during the washing process in which the bottles are heated and washed with water, water-soluble chemical volatile substances are released from the bottles as they are heated and then dissolved in the washing water. Certain hydrocarbons, on the other hand, insoluble in water, may be sampled through the sampling device 22, at the outlet side of the dishwasher, to exclude dissolved water-soluble chemicals. Then, detection of such hydrocarbons can be performed without potentially affecting other water-soluble chemicals if the bottles are passed through the dishwasher prior to testing.

The tested materials are not limited to the substances contained in the containers. For example, the method and system of Fig. 1 can be used to detect volatile substances absorbed by fragmented or sliced bottle material, or a plastic mass from secondary collection for the manufacture of new plastic containers for beverages or other materials. plastic materials. This shredded or shredded plastic load may be placed directly on the conveyor belt 10 and passed through the test station 12 of Fig. 1, or the plastic load may be placed in baskets, buckets or other types of containers placed on the conveyor belt and tested. portions.

The system for analyzing volatile substances emitted from the containers C in the test station 12 in Fig. 1 will be described with reference to the embodiments shown in Fig. 2 as an odor detector. Figure 2 shows a linear conveyor system including a conveyor 198 in which a plurality of plastic containers C move through the first inspection station 200 and into a shredder 202. The fines or lobes F exiting shredder 202 pass through the inspection station 204 where the contaminated lobes are discarded and separated. from the clean sheets F heading to the dishwasher 206. The comminuted or flaked material F exiting the dishwasher 206 is re-inspected at the inspection station 208 where the still contaminated material sheets are discarded. The substantially clean panels F to be used in the production of new containers exit on a conveyor 198 from an inspection station.

Each of the testing stations 200, 204 and 208 in the arrangement of Fig. 2 preferably includes an odor detector, such as the arrangement shown in Fig. 1 for testing station 12.

Of course, additional test stations may follow test station 208. For example, test station 208 may be followed by a pellet device, an additional test station after the new bottle preforming station to test these preforms; another control station after the blow mold which blows the preform of the new bottles.

There are three different process steps in Figure 2 in which the odor detector is most effective for the plastic panels F. The first two sampling points at the control stations 200 and 204 are arranged to remove contaminated material before it enters the dishwasher washing process 206. If the chemical odor detection process at the control stations 200 and 204 is effective, then the efficiency of the dishwasher step 206 is less. critical. This may allow a cheaper and more economical dishwasher 206 to be used.

Testing and sampling of containers C arriving at inspection station 200 of Figure 2 is designed to find most of the contaminants in the containers and minimize mixing of contaminants in subsequent pretreatment steps. The containers C are usually crushed or perforated in this position, and are in a lying rather than standing position. Monitoring will, for example, find bottles that have spilled fluid and contaminate other bottles on their way to grinder 202. This step is important because a bottle full of e.g. motor oil can contaminate a pair of other bottles if the oil spills out.

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Containers C that have passed through the inspection station 200 and are not rejected proceed to shredder 202 where they are shredded into small pieces. A temperature of up to 93.3 ° C is generated, which can release pollutants and can therefore be detected more easily. An additional advantage of sampling the particulate material after it exits the shredder 202 at the inspection station 204 is that the contaminants released from the fines derived from a single contaminated bottle will not contaminate too much of the other material. Thereby, sampling of the vapors from the shredder at the test station 204 can lead to the rejection of the processed stream of material sheets F originating from the bottle in question along with materials from several adjacent bottles.

Sampling at shredder 202, or as close to the freshly shredded material exiting the shredder as possible, is needed to avoid contamination of a large number of flaps F. That is, all contaminated F flaps exiting shredder 202 are immediately detected at inspection station 204 and are discarded to avoid contamination of more of the panels on the conveyor 198.

The third test station 208 is arranged to test the flaps F exiting the dishwasher 206 to monitor the washing process. Again, monitoring is most effective when temperatures are high enough to assist with the emission of volatile pollutants from the material patches. Dishwasher temperatures are typically between 88 ° C and 99 ° C. The monitoring of the washed F sheets is intended to ensure good quality of the later stored products and the detection of contamination at this point in the process will require automatic rejection of a substantially large amount of material due to the mixing of good and bad F sheets in the washing process.

An effect of the present invention is that the temperature of the aqueous solution used in the dishwasher 206, either in the prilling or preform machine, must be kept below the temperature at which the plastic material to be tested would evaporate. Such evaporation can produce a detectable background that would interfere with the detection of contaminants in the materials. For example, tests were performed on panels of PET beverage bottles to determine the ability of the analyzing device of the present invention to test the material without being affected by background volatiles derived from the PET material itself. Six temperatures have been tested as detailed below:

Temperature ° C Observation 26.7 No background was observed in the PET fumes 93.3 No background was observed in the PET fumes 148.9 No background was observed in the PET fumes 204.4 No background was observed in the PET fumes 343.3 No background was observed in the PET fumes 398.9 The background was observed

It can be seen from the above that PET sheets can be subjected to chemical odor detection at temperatures up to about 343.3 ° C without any effect of PET itself on the detection of contaminants in the PET sheets.

However, the highest temperature at which odor detection tests are performed may be at the pelletizing and preforming stations and should not exceed about 298.9 ° C.

Another conclusion from these experiments is that the washing procedure must advantageously remove hot fumes from the process so as not to risk contaminating all PET materials which are in contact with the fumes of the contaminants in the dishwasher. This is an important fact and it distinguishes this dishwasher from previous dishwashers as there has been a tendency in prior art systems to use closed washing systems so as to keep warm and minimize energy costs. Meanwhile, dishwasher 206 has

179 604 a vent, such as a vent 210, to extract hot vapors from the PET panels. The shredder 202 may also include a vent for hot vapors associated with the grinding process.

The present invention is susceptible of various modifications without departing from the scope of the appended claims.

Claims (13)

Patent claims A method of sampling and determining the presence of contaminants in plastic materials from secondary processing and directed to the production of new containers, characterized in that the charge is supplied in the form of used containers, then each container is broken and using the temperature increase resulting from breaking Vaporized possible pollutants emitted in the form of volatile substances are immediately collected from the containers and tested for the presence or absence of pollutants in these materials. 2. The method according to p. The method of claim 1, characterized in that the fragmented plastic material is broken into strips. 3. The method according to p. The method of claim 1, wherein the material to be ground is broken to form sheets of plastic material. 4. The method according to p. The method of claim 1, wherein the test fluid is directed to pieces of material, then moves at least some of the volatile substances emitted from the pieces of material to positions remote from the materials to form a test cloud, and a sample of some of the volatile substances is sampled by suction and then analyzed. by determining the presence or absence of contaminants in the materials. 5. The method according to p. The method of claim 1, characterized in that, before testing the fragmented material, the pieces of plastic material are additionally washed in a heated liquid to remove some of the contaminants contained in it, and the temperature of the washed material is kept below 343.3 ° C, with no emission of vapors from the materials themselves plastic, PTE. 6. The method of sampling and determining the presence of contaminants in plastic materials from secondary processing and directed to the production of new containers, characterized by the fact that a batch of materials from which used containers were produced, the batch of materials is washed in a hot liquid, then some of the impurities contained therein are removed, the temperature of the washed material is kept below 343.3 ° C, volatile impurities are tested to determine the presence or absence of impurities in the PET materials. 7. The method according to p. 6. The method of claim 6, characterized in that during testing, the fluid is directed to pieces of material, moving at least some of the volatile substances contained therein to positions distant from the materials to form a test cloud, and then a sample of the volatile substances is taken by suctioning the test cloud and then the collected sample is analyzed. determining the presence or absence of contaminants in materials. 8. The method of sampling and determining the presence of contaminants in plastic materials moving along the conveyor from used containers, and sorting this material for secondary processing for the production of new containers, characterized by the fact that a batch of used containers is delivered to the conveyor, is tested the used container is used due to the volatile impurities it contains, the contaminated containers are separated from the conveyor, each remaining container is broken and, using the temperature increase occurring when the containers are broken, the pollutants evaporated at this higher temperature and the volatile substances emitted from them are collected, they are tested to determine the presence or absence of impurities in materials, pieces of material containing impurities are separated and removed from the conveyor, pieces of material are washed 179,604 remaining on the conveyor in the hot liquid, test the volatile contamination from the pieces that have been washed, and separate the pieces containing the contaminants from the unpolluted pieces. 9. The method according to p. Method according to claim 8, characterized in that during each test, the fluid is directed to the container or pieces of materials, moving at least some of the volatile substances contained therein to positions remote from the materials to form a test cloud, sampling of the volatile parts by sucking the test cloud in an area remote from the materials, and aliasing the downloaded sample. 10. The method according to p. The method of claim 8 or 9, further comprising maintaining the temperature of the washed material below 343.3 ° C. 11.A system for sampling and determining the presence of contaminants in recycled plastic materials moving along a conveyor, obtained from used containers, and sorting this material for recycling to manufacture new containers, characterized by having a conveyor (198). ) with a stock from used containers (C), the first test station (200) testing used containers (C) for volatile contaminants, after the test station (200) there is a first unit for separating and removing contaminated containers from the conveyor (198) followed by a shredder (202) for each remaining container, a second volatile test station (204), followed by a second unit for separating and removing the pieces of material containing contaminants from the conveyor, a unit for washing (206) the pieces of material remaining on the conveyor. conveyor in hot liquid, further there is a third test station (208) for volatile contaminants from the pieces that have been washed, and finally a third unit for separating the pieces containing contaminants from those containing no contaminants. 12. The system according to p. The method of claim 11, characterized in that each test station (200, 204, 208) includes an assembly for directing the fluid to the container (C) or pieces of materials, a volatile sampling assembly, an aspiration assembly for collecting samples from a cloud in an area remote from the conveyed materials, and a team to analyze the collected sample. The system according to p. The method of claim 11 or 12, further comprising a means for keeping the temperature of the washed material located adjacent to the dishwasher (206) below 343.3 ° C.